Treat the D-pad center button as SDL_SCANCODE_RETURN

This fixes handling of the Android TV remote select button sent over CEC.

src/video/android/SDL_androidkeyboard.c

@@ -94,7 +94,7 @@ static SDL_Scancode Android_Keycodes[] = {
     SDL_SCANCODE_DOWN,             // AKEYCODE_DPAD_DOWN
     SDL_SCANCODE_LEFT,             // AKEYCODE_DPAD_LEFT
     SDL_SCANCODE_RIGHT,            // AKEYCODE_DPAD_RIGHT
-    SDL_SCANCODE_SELECT,           // AKEYCODE_DPAD_CENTER
+    SDL_SCANCODE_RETURN,           // AKEYCODE_DPAD_CENTER
     SDL_SCANCODE_VOLUMEUP,         // AKEYCODE_VOLUME_UP
     SDL_SCANCODE_VOLUMEDOWN,       // AKEYCODE_VOLUME_DOWN
     SDL_SCANCODE_POWER,            // AKEYCODE_POWER